This invention relates generally to video apparatus. More particularly, this invention relates to video apparatus which detects whether composite color video signals or component color video signals are received and which is selectively operable to process either signal in response to the particular signal detected.
In color video systems, the primary color images of a scene are normally converted to matrixed signals for signal transmission and recording. Thus, in the NTSC color system the red, green, and blue images of a scene scanned by a color television camera are matrixed into luminance and chrominance component signals which are then multiplexed to produce a composite color video signal for transmission to a home television receiver. The composite signal is demultiplexed to separate the luminance and chrominance components which are then dematrixed to reproduce the red, blue, and green images which drive respective electron guns in the television receiver. The necessity for multiplexing the luminance and chrominance components into a composite signal for transmission and then for demultiplexing the signal to recover the luminance and chrominance components for use in a television set tend to produce degradation of picture image. Moreover, multiplexing and demultiplexing of the composite color video signal increases circuit complexity in both the transmitter and receiver thus increasing equipment cost. In addition, time base errors may be introduced during recording and reproducing of the composite signal resulting in a number of image artifacts.
Although government regulations presently require broadcast transmission of a composite color video signal, there are a growing number of user applications where composite color video signals are not or do not need to be used. Thus, video cassette recorders (VCRs) and video disc players record color video signal as a component signal. However, in most video equipment, the recorded component signal is multiplexed to a composite signal for local transmission to a TV which demultiplexes the signal. This results in unnecessary image degradation and equipment complexity. Moreover, home video cameras and home computers generate component color video signals which must also be multiplexed and demultiplexed for use with a standard television receiver which only accepts composite color video signals.
Thus, it has been proposed to by-pass use of the composite color video signal by utilizing the component color video signals directly. The use of component video signals results in higher picture resolution and truer color rendition since the full bandwidths of the component signals (e.g., luminance and chrominance components in the NTSC, PAL and SECAM systems, RGB components, etc.) are used without intercomponent interference. Moreover, problems resulting from time base errors are eliminated when the signals are recorded and/or reproduced since the component video signals are separate.
Considering the advantages of utilizing component color video signals, there has arisen a need for providing a technique for video apparatus (such as color TV receivers, color video cameras, color video disc and tape recorders) to automatically detect whether a composite color video signal or a component color video signal is being received and to control the video equipment to process the detected signal. Such a technique is advantageous for user convenience and simplicity and allows transmission of composite color and component color video signals over the same channels, reducing the necessity of separate channels (cables) for each type of signal.